The use of optical and/or optoelectronic devices is increasing in communications applications. These devices are often chips having waveguides and other features. These features can be formed by etching the chip while a patterned mask is positioned on the device. The mask pattern often requires nanometer level resolution in order to reduce the optical loss associated with the chip. Photolithography and electron beam lithography are examples of methods for forming these masks.
Photolithography uses light in order to develop/pattern a photoresist that serves as the mask. As a result, photolithography is suitable for quickly patterning large regions of a mask. However, due to diffraction, the resolution of the photolithography can be below the desired levels. Electron beam lithography can provide higher levels of resolution due to the shorter wavelength electrons in the electron beam. However, the mask in electron beam lithography is formed by drawing the electron beam over an electron-beam resist (e-beam resist) by using the electron beam as a pen. As a result, using electron-beam lithography to pattern large regions of an electron-beam resist can take undesirably long periods of time. As a result, electron-beam lithography is often not suitable for fabrication of these devices.
For the above reasons, there is a need for methods of fabricating optical devices.